Patent GB-985105-A (GB)
IPC: F02B71/04
Abstract: 985,105. Hydrostatic transmissions. INTERNATIONAL HARVESTER CO. March 20, 1962 [May 1, 1961], No. 10608/62. Heading F2C. [Also in Division F1] A free piston engine hydraulic pump 185 is started by an hydraulic system having sources of high pressure (HP) and of extreme high pressure (EHP) which system first prepositions the engine pistons 188 to the start of a compression stroke, charges an accumulator space BKc to EHP, then connects the space BKc to the pump pressure space 197 to drive the engine pistons outwardly on their compression stroke. Engine arrangement.-The free piston pump 185 having opposed pump pistons 192, 193, Fig. 9, actuated by engine pistons 188, 189, is similar to that of Specification 931,232 and forms part of a hydrostatic power transmission system of a tractor, the pump output being the high pressure circuit 198 which feeds a HP accumulator AI and, when desired, rotary hydraulic motors 266 driving the road wheels and hydraulic rams 268 actuating vehicle attachments such as a bulldozer. The engine shown is a four-piston diesel engine each pair of pistons being connected by synchronizing mechanism having a shaft 159 with cams 230, 231, which operate feed injection pumps 214-217. The fuel pump outputs, and hence the engine power output, are controlled by an accelerator pedal 271 connected by a link 279 to the fuel pump control rods 289, 291, which link 279 is also connected to links 294, 295, attached to levers 296, 299, controlling the hydraulic pressures on chambers BKa, CAa, of accumulators BK, CA, and the fuel pump delivery pressure respectively. A low pressure (LP) pump ZA (e.g. 200 p.s.i.) feeding a low pressure accumulator AB which through pipes 196, 199, feeds the inlets of the pump 185, is driven by an electric motor M at starting and through an over-running clutch 164, by an hydraulic motor BQ when the engine has started. The shaft of pump ZA, Fig. 3B, also drives lubricating oil pump H, fuel feed pump O, water pump V and fan U. When the engine has started the hydraulic motor BQ drives pump ZA through a generator G which charges the battery Z and also actuates a relay to Cut out electric motor M. The extremely high pressure accumulator is supplied by an EHP pump AH driven by an electric motor MA at starting and by an hydraulic motor CD during normal running. Starting sequence. First stage-priming.-Operation of starting switch Y energizes EHP pump MA to charge EHP accumulator. AQ and circuit 336, energizes LP pump M to drive accessories and prime all circuits, and actuates solenoid valve AJ, Fig. 3, to supply EHP through 340 to accelerator lock ram AR to the right to free lever 296 and accelerator linkage 270. EHP also flows through 341 to pressure control valve AU and then through 342 to chambers BKa, CAa, to force pistons 18, 18<SP>1</SP> to the left. The pressure in pipe 342 depends upon the load applied to the shuttle of valve AU by spring abutment controlled by lever 296. EHP acts through pipe 337 to move valve AV to the left which moves lever 299 and accelerator linkage 270 to " idle " position. EHP is then transmitted through AV and pipe 350 to rams 272 on the injection pumps 214-217 render the pumps operative by allowing the pump actuating means to move into contact with cans 230, 231 on oscillatory shaft 159, and through pipe 351, pressure control valve AX, and pipe 264 to control means on the injection pumps to control the pressure of the fuel pumps output. When the EHP in accumulator AQ reaches the minimum desired operating pressure, e.g. 9500 p.s.i., set by cut-out switch AM, a normally open relay AN is closed to render the circuit of start button AZ operative. Second stage-positioning of engine pistons.- Pressing of start button AZ closes relay AZ1 to open solenoid operated valve AT which admits EHP through 374 to ram BA which moves lever 296 and accelerator linkage 270 from " idle " to " start " position, whereby fuel pump controls 289, 291 and AX, Fig. 3C, are set to increased fuel supply position and pressure and the loading of valve AU, Fig. 3, is increased which increases the pressure in accumulator spaces BKa, CAa. EHP from AT also flows through BB to delay-action valve BC which moves slowly to the left to initiate stage three; while it is moving, EHP flows through BC and BD (a) to ram BF which operates rack 143 to move the engine pistons, through the synchronizing mechanism, to the start of compression stroke and (b) to ram BG which moves valve BH to the left to cut off the pump high pressure pipe 198 from the HP accumulator AI, in which position BH is held by a spring toggle 149. Third stage-starting impulse.-When delay valve BC has moved to the left BD is actuated to de-energize BG and BF, and EHP from BC flows through BJ to AY and through 390 to charge accumulator space BKc to EHP. The pressure build up in 390 moves valve AY to the right with a snap action which suddenly connects the EHP in space BKc with pump space 197 of engine A, whereby the engine pistons are forced outwardly to complete a compression stroke and the engine fires. Cam 157 trips toggle 149 to open BH whereby the fluid from pump 197 charges accumulator AI. Holding relay BJ is energized through BO to hold AY operative by EHP from AV instead of AT which is de-energized after starting. Fourth stage-de-actuation of starting circuit.- Delay valve BO moves slowly to the right during the third stage and when it is fully actuated it transmits EHP to move BB to the left to shut off EHP from pipes 374, 375 whereby BC and BD are de-actuated. Fifth stage-engine running.-Button AZ is released to open relay AZ1 which de-energizes AT to de-actuate ram BA which frees lever 296 and the accelerator linkage for operation between " idle " and " maximum power" positions. The pump units A, B, draw from low pressure accumulator AE and charge accumulator AI and spaces BKc, CAc, to high pressure, e.g. 5000 p.s.i. The HP from AI drives motors CD and BQ to take over the drives of EHP and LP pumps MA, M, and operates the vehicle propulsion motors 266 and accessory rams 268. When the engine control 271 is at idling, valve AU reduces the pressure in spaces BKa, CAa, and pistons 18 move to the right so that the maximum volume of EHP fluid is stored in spaces BKc, CAc, providing a reserve of fluid which can be discharged instantaneously to the motors 266 to assist acceleration if the accelerator pedal 271 is suddenly depressed. Depression of pedal 271 also causes rod 279 to set the fuel pump controls 282, 283 and AX to higher output and pressure for acceleration. The rod of valve AV prevents the accelerator pedal being moved below "idle " position during normal running. Stopping.-Key Y is turned to off, which deenergizes solenoid valve AJ whereby EHP is cut off from pipe 340 so that ram AR is deenergized and moves lever 296 and accelerator linkage 270 to " stop." The spring of ram AR is strong enough to overcome the force of valve AV, which is still loaded by EHP, so that AV is forced to the right to connect 350 to drain whereby the devices 272 are rendered inoperative and the pump actuating rods are moved away from the cams 230, 231, to render the fuel pumps inoperative and stop the engine. Connection of pipe 350 to drain also deactuates valve AY which cuts the pump space 197 off from accumulator space BKc and connects the latter to drain. The high pressure fluid in accumulator AI continues to drive the accessories motor BQ and the EHP pump motor CD until exhausted. The high pressure and low pressure circuits are exhausted to drain when the motors BQ, CD, stop but the EHP circuit remains under pressure.